Metathesis reactions catalyzed by ruthenium or other transition metal complexes have been widely applied in the synthesis of macrocyclic compounds. (see, e.g. K. C. Nicolaou et al., Angew Chem. Int. Ed. 2005 44:4490-4527). Ring metathesis has been utilized to prepare macrocyclic lactams and peptides. (R. H. Grubbs et al. U.S. Pat. No. 5,811,515; S. F. Martin et al. Tetrahedron Lett. 1994 35(5):691-694; B. C. Bennett et al., Tetrahedron Lett. 1994 35(19):3191-3194)
In WO 2005/037214 published Apr. 28, 2005 by L. M. Blatt et al. and WO 2007/015824 published Feb. 8, 2007 by S. D. Stewert et al. disclosed the RCM of a diene of the formula 2a the presence of a Nolan or Hoveyda catalyst to form the macrocycle of formula 2b.

There is a continuing need for improved ring-closing olefin metathesis catalysts to improve the efficiency and to manufacture complex organic molecules which are useful in the treatment of Hepatitis C Virus. (P. H. Deshmukh and S. Blechert, “Alkene Metathesis: the search for better catalysts” Dalton Trans. 2007 2479; A. Michrowska and K. Grela, “Quest for the Ideal Metathesis catalyst” Pure Appl. Chem. 2008 80(1):31-42)